In theory, it should be reported.  But if there's no one around...
I have hit deer twice.  The first time my car was totaled, so I had to wait around for the men in blue and make an accident report.  The second time there wasn't a soul on the road within 20 miles.  The deer collision made my car do a complete 360, but no major damage and I was off to home with my petal on the metal.